Chasing down a ~400ma drain on my 05 MCS and about losing my mind over it. I traced the issue to the f21 fuse, a member here at posted about his experience with a bad tach, so I went ahead and gave that a second-hand replacement a shot - no dice. Pulled the speedo today to see if I could identify a fault in the wiring from speedo to tach, unplugged that harness to find no improvement. Unplugging the speedo itself provides the same result as pulling the f21 fuse. What's frustrating is that I see a date code on the speedo past the manufacture date of the vehicle, suggesting it has already been replaced. Given the pretty linear mileage on the history of the vehicle, I'm not super concerned that I've bought a high mileage mini by accident, and it seems reasonable that the replacement was done by a dealership - looks as though it has been there some time. Assuming the speedo was not programmed to the ECU, could this mismatch freak out the computers and cause a drain? Trying to eliminate other options before purchasing a second-hand speedo.

Everything seems to function as it should with the exception of the ABS sensor trifecta of lights on the dash. I replaced the drives side sensor and the lights went out for a few days. Planning to replace passenger shortly. Could be related?

A photo for this otherwise boring post

 

I don't have an answer, but that's a nice looking R53.

This thread is on swapping in a chrono pack, but it may shed some light on Kombi VIN mismatch issues. It doesn't seem to me like it would cause a draw all the time, but I don't claim to know enough about all the modules to say whether they would stay awake.

 

Say like those rims!

the fuse has a limited number of items on it so I’d think if you keep after it you’ll find it

 

Thanks, I'm not normally a wheel guy but I'm into these.
Replaced the speedo, seemed a reasonable next step. No dice. I will say, however, the replacement speedo which came from an '05 also has an '06 date code. Maybe I can't read, either way, it seems like my speedo is probably original to the car

 

What’s left on that fuse?

 

@ssoliman this is a great question, I don't think much. I need to spend a bit more time combing through the wiring diagram but it seems as though everything functions as it should with f21 removed, outside of what would show on the tach. Wondering if there is an abs component, tpms switch, or brake switch that could be run off f21. brake lights stay on when the car is shut off with f21 removed.
Alternatively, pulling this fuse might mask an unrelated problem by shutting off communication at a certain level? Mechanical work is fine, this is (probably pretty clearly) outside of my wheelhouse. Getting ready to hand it over to a shop for diagnosis at this point.

 

hold the phone. That does not sound right to me 🤔

 

It does seem odd that the tach would be involved in that. My best guess is that since the brake light is displayed on the tach something somewhere along the line freaks out when it's removed. I'll do some more digging on the diode piece and see if I can't verify the condition of mine. I have made an appointment for the car at an indy shop, though. I have until the 23rd to figure this out myself. It needs an alignment anyway, so having a second look isn't the end of the world. I'd sleep easier if I could figure it out, though. Funny how something that's a non-issue if I just drive the car daily is driving me absolutely bonkers

 

Roger that. Wish I were better with electrical issues…they scare me

curious to know what the shop says

 

Shop says I'm an idiot! Well, not quite, but they knew what was up immediately. The airbag emulators I have installed (aftermarket seats) keep the cluster from going to sleep. Shout out to Paddock Imports in Denver for the huge help

 

Thats good. Thought it was something bigger.

 

Put me in the same club....so many hours/weeks/$ to figure out the same thing. Did you find one that doesn't drain the battery, or do you just live with the light?